These studies represent an initial effort to characterize the sequence of events which lead to the modulation of the rate of cellular cholesterol synthesis in response to exogenous effectors (steroids). Our current approach should generate a data base which will lead to a better understanding of the regulatory process for the control of sterol synthesis. We have data which would suggest that cholesterol may not be the proximal effector of its synthesis. This postulation should cause many to reevaluate current ideas about the regulation of cholesterol synthesis. The potential impact of the latter on current management therapy procedures for lipid associated cardiovascular diseases is unknown, but it could be significant. Clearly we will have to await further studies by this laboratory and others before the true significance of the above can be assessed. The next twelve months should be very illuminating.